This invention relates generally to CT, PET, and MR examinations of the heart, and more specifically to methods and apparatus for automating image generation and review.
Accurate evaluation of the cardiac function, particularly left ventricular (LV) function (e.g., stroke volume, ventricular ejection fraction, regional wall motion) is useful in cardiac diagnosis, guiding patient therapy, determining prognosis, and following the course of a disease. LV function is also a useful component of any comprehensive cardiac diagnostic examination for stable coronary artery disease (e.g., stable angina) and acute cardiac syndromes (e.g., acute myocardial infarction and unstable angina). Measurement of ventricular function complements and supplements other cardiac diagnostic procedures such as cardiac catheterization and coronary artery imaging for vessel patency and myocardial perfusion. In patients with a variety of heart diseases, cardiac function has a better diagnostic and prognostic value than vessel patency. For instance, even if a patient has stenosed coronary arteries as in chronic, stable coronary artery disease, close to normal ventricular function at rest and exercise suggests an excellent prognosis. On the other hand, even with good coronaries and normal perfusion, depressed ventricular function indicates a poor prognosis.
There are several known methods to measure cardiac function including echocardiography (Ultrasound), radionuclide imaging (positron emission tomography (PET)), magnetic resonance (MR) imaging, and computed tomographic (CT) imaging. One disadvantage of the echocardiographic methods is that they are highly operator dependent.
Three-dimensional imaging techniques of the heart are now widely used in several modalities (such as CT, MR, and PET). The review of these 3D datasets by a radiologist usually involves the creation of 2D reformatted slices (also called oblique planes) in specific anatomical orientations. These views are defined according to the long axis of the heart, which is defined as the line that joins the apex of the heart to the center of the mitral valve plane. For example, a Short Axis (SA) plane is the orientation orthogonal to the long axis allowing the visualization of cardiac anatomical structure in a meaningful cardiac plane without any foreshortening or elongation distorting structures and allowing comparison with output created from other cardiac imaging modalities. A SA plane is a cross-sectional view of the left ventricle, which is the standard plane for viewing the functional parameters of the heart. This allows the physician to view the motion of the heart through systole to diastole.
A Horizontal Long Axis (HLA) is the plane defined by the long axis and the four chamber cut plane (approximately the Left to the Right cut plane relative to the patient) allowing the visualization of cardiac anatomical structures in a meaningful cardiac plane without any fore-shortening or elongation distorting structures and allowing comparison with output created from other cardiac imaging modalities. This view allows for a four-chamber view of the heart displaying both the atria and ventricles in one view allowing visualization of the tricuspid and mitral valves.
A Vertical Long Axis (VLA) is the plane orthogonal to the HLA and containing the Long axis, allowing the visualization of cardiac anatomical structures in a meaningful cardiac plane without any fore-shortening or elongation distorting structures and allowing comparison with output created from other cardiac imaging modalities. This view allows for a two-chamber view of the heart displaying both the atria and ventricle of the heart.
An Inflow/Outflow view of the Left Ventricle allows additional views contributing to analysis of cardiac morphology.
The orientation of the heart within the chest may vary from patient to patient, therefore the geometric orientations of these anatomical planes have variability and must be determined specifically for each case.
Moreover, to review efficiently a 3D cardiac dataset, there is a need to display simultaneously several anatomical orientations in different view ports for review, with the images being linked by a common 3D cursor. The configurations of the views on the screen can vary, according to the preference of each physician or according to a specific clinical task.
Known techniques involve manual determination of each of these planes on the screen. This is performed by manually orienting each oblique view, based on other views. Creating several views in different orientations can be very time consuming. Therefore, below are described methods and apparatus which address the above problems, in one embodiment, with a unified automated solution.